<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>Title</title>

</head>
<body>

<div id="app">
  <h1 v-if="ok===true">{{message}}</h1>
  <h2 v-else-if="ok===false">N</h2>
</div>

<!--cdn-->
<script type="text/javascript" src="https://unpkg.com/vue"></script>
<script>
  var vm = new Vue({
    el: "#app",
    data: {
      ok: true,
      message: "hello"
    }
  });
</script>
</body>
</html>